Distribution and pathogenicity of Pythium species from tomato

Nine species of Pythium were isolated from tomato field soil, seedlings and roots from 8 localities in Uttar Pradesh, India. Among these, P. aphanidermatum, P. periplocum, P. spinosum and P. ultimum var. sporangiiferum were isolated from soil and seedlings in summer and winter grown crops. The differential prevalence of Pythium species was closely associated with soil temperature, moisture and organic carbon. From isolation and pathogenicity tests, P. ultimum var. sporangiiferum appeared to be themost ubiquitous and important pathogen, followed by P. spinosum and P. aphanidermatum.